Disease burden in patients with myasthenia gravis depending on the dose of oral corticosteroids: an insurance claims database study in Japan

Makoto Samukawa¹Shingo Konno²Akiyuki Uzawa³Kentaro Taki⁴Hiroshi Todaka⁴Izumi Mishiro⁴Céline Quelen⁵Zuzanna Łukowicz⁶Renata Majewska⁶Yohei Ohashi^4*

• ¹Kindai University School of Medicine, Sayama, Japan
• ²Toho University Ohashi Medical Center, Tokyo, Japan
• ³Graduate School of Medicine, Chiba University, Chiba, Japan
• ⁴UCB, Tokyo, Japan
• ⁵Putnam, London, United Kingdom
• ⁶Putnam, Krakow, Poland

Introduction: Oral corticosteroids (OCS) are used for maintenance treatment of myasthenia gravis (MG). Prolonged use of higher-dose OCS may provoke serious adverse events. Therefore, Japanese clinical guidelines recommend an OCS dose target of ≤5 mg/day. This retrospective study aimed to compare the burden of MG between patients achieving this target and non-achievers. Methods: Data were obtained from three Japanese healthcare databases (JMDC, NHI and LSEHS) between 2014-2021. Patients with MG starting immunotherapy were enrolled and data were collected over two years following start of immunotherapy. Exposure to OCS was determined from medication delivery records; achievers and non-achievers of the ≤5 mg/day target during follow-up were identified. Outcomes evaluated were incident confirmed diabetes, new osteoporotic fracture, and total and MG-related costs. Results: Overall, 459 patients were analyzed. Of these, 94 patients (58.4%) in the JMDC population, 96 (64.0%) in the NHI population and 119 (80.4%) in the LSEHS population achieved the ≤5 mg/day target. Incident confirmed diabetes in the JMDC population and new osteoporotic fractures in the LSEHS population were less frequent in target achievers than in non-achievers (p=0.01 and p<0.05, respectively). In target achievers in the JMDC and LSEHS populations, total and MG-related costs were lower (both p≤0.01) than in non-achievers. Discussion: OCS dose target non-achievers carry a higher burden than achievers. Broader implementation of effective treatment strategies is required to reduce long-term use of higher-dose OCS and the associated burden.